Spring tensioned fuse link



Oct. 26, 1937. A. e. STEINMAYER SPRING iENSIONED FUSE LINK Filed Oct. 1, 1934 dlm'w l A. lllll II. i Jug I- INVENTOR Arroriusv ill Patented Oct. 26; 1937 UNITED STATES PATENT OFFICE SPRING TENSIONED FUSE LINK Application October 1, 1934, Serial No.-'146,4'l9

' 10 Claims. (01. 200-127) This invention relates to improvements in springv tensioned fuse links. I

Spring, tensioned fuse links have heretofore been provided with a flexible leader composed of numerous wires of exceedingly small cross-sec- -tional area. These wires fuse easily and on high voltage currents, where there may be considerable arcing, an extremely large amount of metallic gas is generated when these wires fuse.

Accordingly, it is the principal object of this invention to provide a spring tensioned fuse link having a relatively non-flexible leader of comparatively large cross-sectional area, whereby to prevent fusing of the leader when the fusible portion of the link is destroyedand thereby keep the amount of gas generated by the arc at a minimum.

A further object is to provide a spring tensioned fuse link for expulsion fuses and in which only the conducting portions of the link proper are destroyed or discarded after the fuse blows.

In the drawing:

Fig. l is a view in side elevation partly in section illustrating an embodiment of this invention.

Fig. 2 is a fragmentary view in side elevation of the upper portion of the fuse link shown in Fig. 1.

Fig. 3 is an enlarged plan view as viewed from the bottom of Fig. 1.

Fig. 4 is a sectional view taken on the line l4 of Fig. 1 showing a fragmentary portion of the spring.

Fig. 5 is a fragmentary view in side elevation showing a modified form of this invention.

Fig. 6 is a view similar to Fig. 1 illustrating a modification of this invention.

Thruout the several views like parts are identifled by the same reference characters.

In Fig. 1 the fuse cartridge comprises a tube of insulating material Hi open at the lower end and having at its upper end a contact ferrule ii closed by means of a cap l2. Adjacent the lower end of the tube' iii, a contact I! is provided having a clamping nut I l engaged with the stud I! thereon.

The fuse link shown in Fig. 1 comprises a contact button It secured to the ferrule II by means of the cap II, a terminal portion l'l apertured at It and I! and having a reduced area 2. at its lower end provided with an aperture 2|, a

fusible section 22 having its upper end passed thru the aperture 2| and coiled about the ter-.

minal portion II at 22A, a leader composed of a strip of metal bent intermediate its ends to provide an eye portion 23 and conducting portions 24 extending from the open 'end of the tube II, the lower end of the fusible section 22 being passed thru the eye portion 23 and coiled about the conducting portions 24 at 223 adjacent the eye portion 23. The fusible section 22 may be soldered at each end to the terminal portion l1 and the conducting portions 2!, the solder not being illustrated so that the manner in which the several elements are secured together may be clearly shown.

At the lower end of the tube It, a coil spring 25 is provided encircling the lower ends of the conducting portions 24 of the link and having a portion 25 extending upwardly and hooked over the stud I! to be clamped to the contact II by means of the clamping nut ll. Secured to the other end of the spring 25 by means of solder or otherwise, is a washer 21 flanged at 28 to partly encircle the lower end of the spring 25 and provided with a centrally located flanged opening 29 having its walls slotted at l! to receive the lower ends of the conducting portions 24 of the fuse link when bent radially'outwardly as illustrated at 3i J Conducting portions 24 of the leader are illustrated in Figs. 1, 2 and 3 as of the ribbon type.

,In Fig. 5 the conducting portions 24A of the leader are illustrated as cylindrical and shaped to provide an eye portion 23A for securing the fusible section 22 to the leader in much the same manner as that previously described with reference toFigs. 1 and 2. The modified structure shown in Fig. 6 is identical with the structure shown in Fig. 1 except at the lower end where the coil spring 25A encircles the lower end of the tube HI and is provided with a washer 2IA similar to the washer 21 in Fig. l, but enlarged diametrically to receive the end of the tube within the flange 28A. The spring 25A may be secured to the washer 21A by soldering or otherwise and is provided with vertically extend-' ing portion "A engaging the stud II and secured thereto by means of the clamping nut I 4. As shown in Fig. 6 the washer 21A is electrically connected to the contact I 3 by means of a flexible leader 32 secured to the washer in any suitable manner such as soldering, and clamped to the contact I! by means of the clamping nut-ll. Obviously, the washer 21 shown in Fig. 1 may be likewise electrically connected with the contact ll.

The fuse link is inserted in the tube ll thru the upper end thereof when the cap l2 is re moved and is secured thereinwith the contact button l6 clamped to the ferrule II as illustrated. After the link has been thus inserted in the tube, the lower ends of the conducting portions 24 are bent as illustrated at 3| after the spring 25 has been compressed to exert pressure upon the washer.2'l and thus place the fusible section 22 under stress. When the fusible section 22 is severed, the spring 25 will move the .remaining lower portion of the fuse link thru the open end of the tube l0 and impart thereto an expelling motion which will cause that portion of the fuse link to continue its movement until it has cleared the tube.

When the fusible section 22 has fused, an arc will be drawn in that section and will be extinguished before the lower ends of the conducting portions 24 have broken their contact with the washer 21. Thus, all arcing will be confined within the tube where it will not injure any of the portions that are permanently a part of the carshown in Fig. 6. In Fig. 6 the spring 25A is guided by the lower end of the tube I0 and will therefore be maintained in alignment with the tube after the fuse link has been destroyed. However, the flexible leader 32 will serve to conduct the major portion of the current and thereby protect the spring 25A against overheating under excessive current loads. l

I claim:

1. In combination with an expulsion tube comprising an insulating tube closed at one end by a contact and having adjacent its other end and exteriorly thereof a second contact, a fuse link in said tube connected with the first mentioned contact and including a fusible section and a leader section of relatively large cross-sectional area extending thru the open end of said tube, a coil spring at the lower end of said tube connected at one. end with the second mentioned contact engaged with the other end of said spring remote from the tube, said leader section extending thru the spring and aperture in said washer and having'its extremity in hooked engagement therewith to maintain said spring under compression, whereby when the fuse section is fused, the leader section will be expelled from said tube.

2. In combination with an expulsion tube comprising an insulating tube closed at one end by a contact and having adjacent its other end and exteriorly thereof a second contact, a fuse link in said tube connected with the first mentioned contact and including a fusible section and a leader section of relatively large crosssectionalarea extending thru the open end of said tube, a coil spring at the lower end of said tube connected at one end with the second mentioned contact exteriorly of said tube, an apertured washer engaged with the other end of said spring remote from the tube, said leader section extending thru the spring and aperture conducting sections comprising a pair of spacedparalleling wires extending exteriorly of said tube, said fusible section being secured to the leader portion by passing one end thereof thru said eye and coiling it about said conducting sections at a point spaced from said eye.

4. An expulsion fuse including-a tube open at its lower end having a pair of spaced contacts, a fuse link in said tube connecting said contacts, said fuse link comprising a fusible section in said tube adjacent the upper end thereof and a relatively non-flexible section extending from said fusible section through the open end thereof, a coil spring coaxial with and engaged with said tube, said spring being disposed at the open end of the tube and secured to one of said contacts, said relatively rigid section extending through said spring and being bent radially of the tube to hold the spring under compressionand to maintain said fuslble'section under tension, and flexible means electrically conriecting said relatively rigid section with one of said contacts.

5. An expulsion fuse including a coil tube extending from said fusible section through the open end of said tube having a pair of relatively spaced contacts, a fuse link in said tube for electrically connecting said contacts; said fuse link comprising a fusible section and a relatively nonflexible section, a spring tensioning the fusible flexible leader electrically connecting said washer and last mentioned contact.

6. An expulsion fuse including a tube open at its lower end and having a pair of spaced con-.

tacts, a fuse link in said tube, said fuse link comprising a fusible section in said tube and a pair of relatively non-flexible sections extending from said fusible section to the exterior of said tube, a coil spring coaxial with and engaged by'the open end of said tube, said pair of conducting sections being bent radially relative to the tube and in opposite directions-to hold said spring under compression and to maintain said fusible section under tension, and a flexible leader electrically connecting the relatively non-rigid sec-- bent radially of said tube to engage the spring and thereby to exert a tension on said fusible section, said spring being connected at one end with one of said contacts.

8. An expulsion fuse including a tube having a pair of spaced contacts, a fuse link in said tube for electrically connecting said contacts and comprising a fusible section, and a relatively nonflexible section bent to form a pair of paralleling conducting portions extending exteriorly of said tube, a coil spring coaxial with and engaged with said tube, said conducting portions being bent radially of said tube to hold said spring under compression and thereby to exert a tension on said fusible section, said spring being connected at one end with one of said contacts, and a flexible leader electrically connecting the conducting portions of said fuse link with the last mentioned contact.

9. An expulsion fuse including a tube open at its lower end and having a pair of spaced con tacts, one of which is adjacent the open end, a fuse link in said tube electrically connecting said contacts, said fuse link comprising a fusible section in said tubeadjacent the upper end thereof and a relatively non-flexible section extending from said fusible section and through the open end of said tube, and a coil spring coaxial with and engaged with said tube, said spring being disposed at the open end and exteriorly of the tube and secured at one end to said contact adjacent said open end, said relatively rigid section extending through said spring and being bent radially of the tube and spring to releasably engage and hold the spring under compression and to maintain said fusible sectionv under tension, whereby when said fusible section has fused, said non-flexible section will drop freely from said tube and said spring will. remain with said tube.

10. A fuse link in combination with an expulsion fuse cartridge open at one end and a coil spring secured to said cartridge and mounted exteriorly thereof adjacent said open end, said link comprising a contact portion within said cartridge, a relatively rigid leader extending from said open end, and a fusible portion within said cartridge electrically connecting said contact portion and rigid leader, said relatively rigid leader comprising a plurality of elongated rigid wires each extending from said cartridge and through the coils of said spring and being substantially coextensive in length, said wires being connected with each other and with said fusible portion at their corresponding ends and being in spaced and approximate parallel relation from said corresponding ends to the exterior of said cartridge, the ends of the wires exteriorly of said cartridge being bent radially of said coils, thereby to hold said spring under compression and releasable therefrom.

ALWIN G. STEINMAYER. 

